A pod is an external structure attached to the underside of an aircraft which contains navigation, targeting or other equipment. Because of power dissipated by electronic equipment contained in a pod, it has been necessary to cool the pod to maintain proper operation of electronics contained therein.
FIG. 1 illustrates a prior art liquid pod cooling system. Parts of the cooling system have been functionally labeled. In practice, these systems have proved satisfactory to maintain proper temperatures of electronics contained within the pod. However, a number of problems exist with the liquid pod cooling systems. In the first place, coolant liquids, such as Coolanal.RTM. which are placed in contact with electronics in the pod to provide cooling may, if contaminated, become flammable. The possible flammability of cooling liquids is an area of concern in fighter aircraft. Furthermore, it may not be desirable to utilize cooling liquids for certain types of electronics. Finally, liquid cooling systems for pod electronics are rendered inoperative by fluid leaks in the liquid cooling system. As illustrated in FIG. 1, the liquid cooling system 10 for a pod electronics load 12 consists of a first liquid loop 14 and a second liquid loop 16. The first loop 14 has a liquid, such as Coolanal.RTM. 25, flowing through the pod electronics load 12 which is cooled by ram air as indicated in the top of FIG. 1. This loop is utilized without operation of the compressor when the temperature of the ram air is sufficiently low to provide the necessary degree of cooling to the pod electronics load 12. Furthermore, a conventional vapor cooling system is provided which circulates cooled liquid in the second loop 16 when the air temperature of the ram air is insufficient to cool the liquid to a degree to provide necessary cooling for the pod electronics load 12. The operation of the vapor cooling cycle is conventional and is not herein further described.